Bottom wad for cartridge cases, especially shot cartridge cases

ABSTRACT

A bottom wad for cartridges, especially shot cartridges, comprising a cylindrical portion of a thermoplastic synthetic material such as synthetic resin having a front recess for the accommodation of a powder charge. A cylindrical plug is inserted in a rear recess of the cylindrical portion, and both the cylindrical plug and cylindrical portion have a common central, coaxial bore for the reception of primer.

United States Patent 1191 1111 3,756,156 Schuster Sept. 4, 1973 [54] BOTTOM WAD FOR CARTRIDGE CASES, 3,229,634 l/1966 Moelman et a1. 102/42 R ESPECIALLY SHOT CARTRIDGE CASES 2,936,709 5/1960 Seavey 102/44 3,157,121 11/1964 Daubenspeck et a1. 102/44 X Inventor: Ernst Schuster, g. Germany 3,577,924 5 1971 Findlay 102/42 R [73] Assignee: Dynamit Nobel Aktiengesellschaft,

Tmlsdmf, Germany Primary ExaminerRobert F. Stahl [22] Filed: Dec. 2, 1970 Att0rneyCraig, Antonelli, Stewart & Hill Appl. 190.; 94,329

[57] ABSTRACT A bottom wad for cartridges, especially shot cartridges, comprising a cylindrical portion of a thermoplastic synthetic material such as synthetic resin having a front recess for the accommodation of a powder charge. A cylindrical plug is inserted in a rear recess of the cylindrical portion, and both the cylindrical plug and cylindrical portion have a common central, coaxial bore for the reception of primer.

15 Claims, 6 Drawing Figures PATENTEDSEP 4 I975 INVENTOR ERNST SCHUSTER BY AM, W k240i ATTORNEYS BOTTOM WAD FOR CARTRIDGE CASES, ESPECIALLY SHOT CARTRIDGE CASES BACKGROUND OF THE INVENTION The present invention relates to a bottom wad for cartridges, especially shot cartridges.

Cartridge cases such as shot cartridges or the like are in most cases manufactured from several parts, such as a case shank and a bottom section which are joined to each other in a zone of the bottom by pressure. Often, pressed cardboard is employed for the bottom plugs. However, it is likewise conventional to manufacture the bottom plugs from pressed fibrous compositions or from a thermoplastic snythetic resin. Furthermore, bottom plugs are known which consist of a hollow body produced from a snythetic resin and provided with a loose filling of wood, shavings, or the like.

As is known, as essential prerequisite for the usefulness of such cartridge cases is a sufficiently tight seal between the case shank and the bottom section or piece. However, such seal can be achieved, in many cases, only with great difficulties, or it cannot be effected at all when, for example, employing thin-walled tubes of a thermoplastic synthetic resin for the case shank because, upon firing, the thin plastic tubes expand under the pressure of the propellant gases, much more readily in the radial direction than the bottom plugs which are inherently substantially harder and also more solid. Consequently, an unkown and undeterminable amount of propellant gas escapes, thereby modifying the previously calculated and predetermined values in an uncontrollable manner and thus correspondingly impairing the properties of the cartridges.

The same unsatisfactory results are produced when using the relatively expensive and massive or solid bottom plugs of a thermoplastic synthetic resin, insofar as they are sufficiently hard to be usable for pressing the case bottoms. As is known, the bottom plugs, in addition to having a sealing function, must often also fulfill the task of transmitting the compressive forces for the formation of the case botton during the manufacture of the cartridge cases. Moreover, the bottom plugs, by means of their hardness as well as by the firmness of their seating in the case shank, influence the percussion sensitivity of the primer and have an effect on the internal ballistics of the cartridges due to the volume and the configuration of these plugs. As a result, the bottom plugs must have a sufiicient hardness in the zone of the case bottom as exhibited, for example, by hard-pressed cardboard plugs or massive plugs of a relatively hard plastic. The above-mentioned bottom plugs of hollow bodies of a synthetic resin with fillings of loose materials are, however, unsatisfactory for most of the manufacturing methods employed. On the other hand, the conventional and above-mentioned cardboard plugs cannot be manufactured and processed in any desired or required shape and size, especially not with configurations of the recesses for the powder which are favorable from the viewpoint of internal ballistics, and with elastic sealing lips at the front end.

SUMMARY OF THE INVENTION It is an aim of the present invention to overcome the problems and disadvantages encountered in the prior art by providing a bottom wad meeting all requirements to a sufficient extentwithout having to contend with other disadvantages.

The foregoing problems have been solved, in accordance with the invention, by means of a bottom wad or plug characterized by a cylindrical portion and produced from a thermoplastic synthetic material such as, for example, polyethylene, with a front recess for the accommodation of the powder charge, as well as by a cylindrical plug of cardboard and/or fibrous material and/or a mineral substance inserted in a rear recess of the cylindrical portion, wherein the cylindrical portion and the cylindrical plug have a common central, coaxial' perforation or bore for the reception of the primer.

By the combination of the cylindrical portion of a thermoplastic synthetic material with the relatively hard cylindrical plug of cardboard or the like, which plug can be designed in a very simple manner with respect to the shape thereof, a sufficient seal is attained, on the one hand, but the hardness of the cartridge bottom necessary for the flawless seat of the primer and thus a high percussion sensitivity is, on the other hand, likewise ensured.

Apart from the above, it is possible to meet without difficulties the necessary requirements regarding the internal ballistics as well as the configuration of the front recess of the plastic portion required for the most advantageous priming of the respectively employed type of powder. This is so because the cylindrical plastic portion can be manufactured very economically in any desired or suitable or required shape and dimension. Especially favorable results are attained by utilizing as the material an elastic, preferably halogen-free thermoplastic synthetic material, especially on the basis of olefinic hydrocarbons, such as, for example, polyethylene. In this connection, the plastic can be colorless or also dyed in any desired manner.

According to a further feature of the present invention, in the interest of a particularly satisfactory and secure fastening of the plug in the plastic portion, provides annular grooves in the rear recess of the plastic portion presses the plug into these grooves.

An especially good seal between the case shank and the bottom wad of the cartridge case is attained if, according to a further feature of the present invention, the plastic portion is constructed so that it terminates at the front end in a thin, annular lip. According to another feature of the present invention, however, the provision can also be made to design the front end of the cylindrical portion as a support or seat for an intermediate substance of the cartridge. In the latter case, it is possible to attain without difficulties a feasible compromise between the elasticity desired for sealing reasons and the size of the supporting surface required for a secure seating of the intermediate medium.

BRIEF DESCRIPTION OF THE DRAWING These and other aims, features and advantages of the present invention wil become more apparent from the following description when taken in conjunction with the accompanying drawing which shows, for purposes of illustration only, several embodiments in accordance with the present invention and wherein:

FIG. 1 is an axial sectional view of a cartridge with the bottom wad of the present invention;

FIG. 2 is a cross-section axial view of an embodiment of the cylindrical plastic portion;

FIG. 3 is a cross-sectional axial view of another embodiment of the cylindrical plastic portion;

DETAILED DESCRIPTION OF THE DRAWING Referring now to the drawing and, in particular, to FIG. 1, the shot cartridge case includes a plastic tube 1 and a cylindrical plastic portion 2 provided in the rear end thereof. In a recess 3 which is defined by an annular wall 11 and an end wall 12 of the plastic portion 2 and which is provided with annular grooves 4, the bottom wad 5, which consists of, for example, cardboard, is accommodated. Portion 2 and plug 5 have a common central, axial perforation 6 for receiving primer. The front zone of part 2 is provided with the recess 7 to receive the powder, and the shape of this recess is selected so that the elastic annular lip 8 is formed at the front end of portion 2 to afford the advantage of a particularly good seal between the tube 1 and the portion 2 against the powder gases after the firing of a shot. In order to reinforce the case bottom and, in particular, also the extractor rim of the case, there is provided a bottom capsule 9 which is manufactured from a material of a high strength, especially a metal.

The assembly of the individual components can be executed in various ways, such as, for example, first the bottom wad 5 is introduced into the recess 3 of the cylindrical plastic portion 2 and then both of these components are inserted together in the rear end of the plastic tube case 1, whereupon the bottom cap 9 is inverted over the rear end of the tube 1 and all the parts are pressed together so that the wad 5 is pressed into the annular grooves 4 of portion 2 and the tube 1 as well as the portion 2 are deformed at the rear end in the desired manner and finally, the bottom cap 9 obtains the illustrated configuration in the zone of the central perforation 6.

The form of the cylindrical plastic portion 2 shown in FIG. 2 corresponds to that of the cartridge of FIG. 1. The front recess 7 for receiving the powder is constructed, in addition to the consideration of the re- 1 quirements of the cartridge to be produced with respect to the internal ballistics thereof, in such a manner that the annular lip 8 is formed at the front end. The rear recess 3 for the reception of the bottom wad is provided with the annular grooves 4 or, in place of these grooves 4, it is also possible to provide differently shaped and designed grooves or the like such as, for example, a helical groove.

The plastic portion 2 of FIG. 3 differs from that of FIG. 2 by the somewhat different design of the front zone. The front recess 7 is constructed, again taking into consideration the requirements for the cartridge to be manufactured from the viewpoint of internal ballistics, in such a manner that the annular support surface 10 is formed at the front end for supporting an intermediate substance or the like. Whereas the design of FIG. 2 is especially suitable for powder types which are to be loaded under pressure, the embodiment of FIG. 3 can be advantageously employed also when using pure nitrocellulose powders.

The bottom wad 5 of FIG. 4 which can be made, for example, of cardboard and provided with the continuous central bore 6 has a larger axial extension than the recess 3 of the portions 2 of FIGS. 2 and 3. However, this axial extension is dimensioned so that the wad adapts itself with an exact fit to the recess 3 during the subsequent axial pressing operation under a simultaneous, corresponding enlargement in its radial dimensions and penetration into the annular grooves 4 of portion 2.

It is also obvious that the plastic tube 1 of FIG. 5 and the bottom cap 9 of FIG. 6, both of which are shown only for the sake of completeness, are designed and dimensioned in correspondence with the respective practical requirements, especially in adaptation to the bottom plug, so that the respectively desired properties of the cartridge to be produced are attained.

While I have shown and described several embodiments in accordance with the present invention, it is to be clearly understood that the same is susceptible of numerous changes and modifications as will be apparent to one skilled in the art, and I, therefore, do not wish to be limited to the details shown and described herein but intend to cover all such changes and modifications as are encompassed by the scope of the present invention.

I claim:

1. Bottom wad for cartridge cases, especially shot cartridge cases, comprising a cylindrical portion defining a front recess for the accommodation of a powder charge and a rear recess, and a cylindrical plug of a relatively hard material selected from the group consisting of cardboard, fibrous material and a mineral substance inserted in the rear recess of the cylindrical portion, the rear recess being defined by an annular wall and an end wall, said cylindrical plug abutting only along the annular wall and end wall defining the rear recess.

2. Bottom wad according to claim 1, wherein the cylindrical portion and the cylindrical plug have a common central, coaxially extending perforation for receiving primer.

3. Bottom wad according to claim 2, wherein the cylindrical portion is made of a thermoplastic synthetic material.

4. Bottom wad according to claim 3, wherein the thermoplastic synthetic material is polyethylene.

5. Bottom wad according to claim 1, wherein the rear recess of the cylindrical portion is provided with annular grooves, and the cylindrical plug is insertable into these grooves along the periphery therof.

6. Bottom wad according to claim 5, wherein the cylindrical portion and the cylindrical plug have a common central, coaxially extending perforation for receiving primer.

7. Bottom wad according to claim 6, wherein the cylindrical portion is made of a thermoplastic synthetic material.

8. Bottom wad according to claim 1, wherein the cylindrical portion terminates in a thin annular lip at the front end thereof.

9. Bottom wad according to claim 8, wherein the cylindrical portion and the cylindrical plug have a common central, coaxially extending perforation for receiving primer.

10. Bottom wad according to claim 9, wherein the cylindrical portion is made of a thermoplastic synthetic material.

11. Bottom wad according to claim 10, wherein the rear recess of the cylindrical portion is provided with ing primer.

14. Bottom wad according to claim 13, wherein the cylindrical portion is made of a thermoplastic synthetic material.

15. Bottom wad according to claim 13, wherein the rear recess of the cylindrical portion is provided with annular grooves, and the cylindrical plug is insertable into these grooves along the periphery thereof. 

1. Bottom wad for cartridge cases, especially shot cartridge cases, comprising a cylindrical portion defining a front recess for the accommodation of a powder charge and a rear recess, and a cylindrical plug of a relatively hard material selected from the group consisting of cardboard, fibrous material and a mineral substance inserted in the rear recess of the cylindrical portion, the rear recess being defined by an annular wall and an end wall, said cylindrical plug abutting only along the annular wall and end wall defining the rear recess.
 2. Bottom wad according to claim 1, wherein the cylindrical portion and the cylindrical plug have a common central, coaxially extending perforation for receiving primer.
 3. Bottom wad according to claim 2, wherein the cylindrical portion is made of a thermoplastic synthetic material.
 4. Bottom wad according to claim 3, wherein the thermoplastic synthetic material is polyethylene.
 5. Bottom wad according to claim 1, wherein the rear recess of the cylindrical portion is provided with annular grooves, and the cylindrical plug is insertable into these grooves along the periphery therof.
 6. Bottom wad according to claim 5, wherein the cylindrical portion and the cylindrical plug have a common central, coaxially extending perforation for receiving primer.
 7. Bottom wad according to claim 6, wherein the cylindrical portion is made of a thermoplastic synthetic material.
 8. Bottom wad according to claim 1, wherein the cylindrical portion terminates in a thin annular lip at the front end thereof.
 9. Bottom wad according to claim 8, wherein the cylindrical portion and the cylindrical plug have a common central, coaxially extending perforation for receiving primer.
 10. Bottom wad according to claim 9, wherein the cylindrical portion is made of a thermoplastic synthetic material.
 11. Bottom wad according to claim 10, wherein the rear recess of the cylindrical portion is provided with annular grooves, and the cylindrical plug is insertable into these grooves along the periphery thereof.
 12. Bottom wad according to claim 1, wherein the wall thickness of the cylindrical portion narrows in the zone of the front recess toward the front end thereof so that an annular support means is formed for supporting an intermediate cartridge substance.
 13. Bottom wad according to claim 12, wherein the cylindrical portion and the cylindrical plug have a common central, coaxially extending perforation for receiving primer.
 14. Bottom wad according to claim 13, wherein the cylindrical portion is made of a thermoplastic synthetic material.
 15. Bottom wad according to claim 13, wherein the rear recess of the cylindrical portion is provided with annular grooves, and the cylindrical plug is insertable into these grooves along the periphery thereof. 